A method of making a balance-compensated (bc) rotary actuator for use in a rotatable bc head stack assembly (hsa) portion in a disk drive based upon track-follow characteristics of a rotatable test hsa portion is provided. The test hsa portion includes a test rotary actuator having a test actuator weight specification. The test rotary actuator has an actuator body portion, a test pivot axis extending through the actuator body portion and a head connected to the actuator body portion. The test rotary actuator is controlled to rotate about the test pivot axis for positioning the head over a selected disk track. The test rotary actuator has a test rotary actuator center-of-gravity torque vector associated therewith about the test pivot axis. The method provides for vibrating the disk drive at a vibration frequency in order to vibrate the test hsa portion. Position error information is read using the head while performing a track-follow operation during the vibrating of the test hsa portion. head off-track error due to the vibration of the disk drive is derived based upon the read position error information representative of positioning of the head relative to the selected disk track. A resultant torque vector is derived based upon the head off-track error. The resultant torque vector has a magnitude equal to a mass of the test hsa portion times a distance between the test pivot axis and a test installed hsa portion center-of-gravity. The test installed hsa portion center-of-gravity takes into consideration forces acting upon the test rotary actuator due to installation with the test hsa portion. The resultant torque vector has a direction extending perpendicular from the test pivot axis towards the test installed hsa portion center-of-gravity. A balancing torque vector is derived having a magnitude equal to and a direction opposite of the resultant torque vector. The balancing torque vector is incorporated into the test actuator weight distribution specification to produce a bc actuator weight distribution specification. The bc actuator weight distribution specification is used to manufacture the bc rotary actuator having a bc pivot axis. The bc hsa portion has a bc hsa installation center-of-gravity at the bc pivot axis for mitigating external acceleration applied to the bc rotary actuator about the bc pivot axis due to external linear acceleration experienced by the disk drive during a track-follow operation.
|
1. A method of making a balance-compensated (bc) rotary actuator for use in a rotatable bc head stack assembly (hsa) portion in a disk drive based upon track-follow performance of a rotatable test hsa portion, the test hsa portion including a test rotary actuator having a test actuator weight distribution specification, the test rotary actuator having an actuator body portion, a test pivot axis extending through the actuator body portion and a head connected to the actuator body portion, the test rotary actuator being controlled to rotate about the test pivot axis for positioning the head over a selected disk track, the method comprising the steps of:
a) vibrating the disk drive at a vibration frequency in order to vibrate the test hsa portion; b) reading position error information using the head while performing a track-follow operation during the vibrating of the test hsa portion; c) determining head off-track error due to the vibration of the disk drive based upon the read position error information representative of positioning of the head relative to the selected disk track; d) deriving a resultant torque vector based upon the determined head off-track error, the resultant installed torque vector having a magnitude equal to a mass of the test hsa portion times a distance between the test pivot axis and a test installed hsa portion center-of-gravity, the test installed hsa portion center-of-gravity taking into consideration forces acting upon the test rotary actuator due to installation with the test hsa portion, the resultant torque vector having a direction extending perpendicular from the test pivot axis towards the test installed hsa portion center-of-gravity; e) deriving a balancing torque vector having a magnitude equal to and a direction opposite of the resultant torque vector; f) producing a bc actuator weight distribution specification based upon the test actuator weight distribution specification and the balancing torque vector; and g) using the bc actuator weight distribution specification to manufacture the bc rotary actuator having a bc pivot axis, the bc hsa portion having a bc installed hsa center-of-gravity at the bc pivot axis for mitigating external acceleration applied to the bc rotary actuator about the bc pivot axis due to external linear acceleration experienced by the disk drive during a track-follow operation.
2. The method of
3. The method of
4. The method of
5. The method of
6. The method of
i) transforming the read position error information to frequency domain by applying a digital Fast Fourier Transform algorithm to obtain a power spectral density of the read position error information; ii) calculating the peak amplitude of the head off-track error due to the sinusoidal vibration of the disk drive based upon an amplitude of the power spectral density at the predetermined frequency of vibration of the disk drive; and iii) converting the peak amplitude to a percent off-track.
7. The method of
8. The method of
9. The method of
10. The method of
11. The method of
12. The method of
13. The method of
14. The method of
15. The method of
16. The method of
17. The method of
|
1. Field of the Invention
The present invention relates generally to hard disk drives, and more particularly to a method of making a balance-compensated (BC) rotary actuator for use in a rotatable BC head stack assembly (HSA) portion in a disk drive based upon track-follow characteristics of a rotatable test HSA portion.
2. Description of the Prior Art
A representative disk drive incorporating the structures referred to herein is taught, for example, in U.S. Pat. No. 5,953,183 to Butler et al., entitled "HEAD STACK ASSEMBLY FOR A MAGNETIC DISK DRIVE WITH A PASS-THROUGH FLEX CIRCUIT CABLE," and is incorporated herein by reference.
A disk drive includes a disk having a track, a disk controller for generating a servo control signal, and a head stack assembly. The head stack assembly includes a rotary actuator and a flex cable assembly. The rotary actuator includes an actuator body portion, a pivot axis extending through the actuator body portion, and a head extending from the actuator body portion. The rotary actuator is responsive to the servo control signal for positioning the head over the track.
The flex cable assembly includes a flex circuit cable, a flex clamp and electrical components (e.g., an integrated circuit containing a pre-amplifier). The flex cable is interposed between a printed circuit board assembly and the integrated circuit. The head stack assembly includes a rotatable head stack assembly (HSA) portion which includes a rotatable flex cable portion for receiving the servo control signal and the rotary actuator. As such, the rotatable HSA portion includes those subcomponents of the head stack assembly which are configured to rotate about the pivot axis.
It is known that gravitational effects on a mass of the attached flex cable portion and other components of the head stack assembly produce a torque on the rotary actuator about an axis which extends perpendicularly from the pivot axis. Such a torque is undesirable as the rotary actuator becomes susceptible to an external acceleration torque being applied to the rotary actuator about the pivot axis when the disk drive is exposed to an external linear acceleration. The external linear acceleration may be due to vibration or shock for example. The resulting external acceleration torque results in positional errors of the heads relative to the desired tracks (off-track errors) being introduced into the system during operation.
Off-track errors are particularly undesirable for a number or reasons. In particular, such errors directly impact the overall seek time of the disk drive because the settling time will increase. Further, the data transfer rate will decease due to the off-track errors. Moreover, as the tracks per inch (TPI) specification of disk drives increase, the system sensitivity of such off-track errors likewise increases.
There have been attempts to mitigate against gravitational effects of the mass of the flex cable and other components which produce a torque applied to the rotary actuator. In this regard, a known methodology includes estimation of which portion of the flex cable is associated with a gravitational related torque applied to the rotary actuator related to the mass of the flex cable, in addition to the mass other components of the head stack assembly. For example, half of the flex cable may be a rough estimate. The prior art method would call for cutting the flex cable at the estimated location and removing the rotary actuator with the severed portion of the flex cable. The center of gravity of the rotary actuator with the severed portion of the flex cable would then be determined by mechanical means. Using such center of gravity information, the rotary actuator design would then be modified so as to attempt to locate the center of gravity of the rotary actuator with the severed portion of the flex cable at the pivot axis. Such prior art rotary actuator designs have proven to include a high degree of off-track errors associated with external linear acceleration acting on the disk drive. Accordingly, there is a need in the art for a method of making an improved rotary actuator as incorporated in a disk drive.
An aspect of the invention can be regarded a method of making a balance-compensated (BC) rotary actuator for use in a rotatable BC head stack assembly (HSA) portion in a disk drive based upon track-follow characteristics of a rotatable test HSA portion is provided by the present invention. The test HSA portion includes a test rotary actuator having a test actuator weight distribution specification. The test rotary actuator has an actuator body portion, a test pivot axis extending through the actuator body portion and a head connected to the actuator body portion. The test rotary actuator is controlled to rotate about the test pivot axis for positioning the head over a selected disk track. The test rotary actuator has a test rotary actuator center-of-gravity torque vector associated therewith about the test pivot axis. The method provides for vibrating the disk drive at a vibration frequency in order to vibrate the test HSA portion. Position error information is read using the head while performing a track-follow operation during the vibrating of the test HSA portion. Head off-track error due to the vibration of the disk drive is derived based upon the read position error information representative of positioning of the head relative to the selected disk track. A resultant torque vector is derived based upon the head off-track error. The resultant torque vector has a magnitude equal to a mass of the test HSA portion times a distance between the test pivot axis and a test installed HSA portion center-of-gravity. The test installed HSA portion center-of-gravity takes into consideration forces acting upon the test rotary actuator due to installation with the test HSA portion. The resultant torque vector has a direction extending perpendicular from the test pivot axis towards the test installed HSA portion center-of-gravity. A balancing torque vector is derived having a magnitude equal to and a direction opposite of the resultant torque vector. The balancing torque vector is incorporated into the test actuator weight distribution specification to produce a BC actuator weight distribution specification. The BC actuator weight distribution specification is used to manufacture the BC rotary actuator having a BC pivot axis. The BC HSA portion has a BC HSA installation center-of-gravity at the BC pivot axis for mitigating external acceleration applied to the BC rotary actuator about the BC pivot axis due to external linear acceleration experienced by the disk drive during a track-follow operation.
Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only, and not for purposes of limiting the same,
Referring now to
Referring to
Referring now to
The actuator assembly 28 further includes a coil portion 42. The coil portion 42 extends from the actuator body portion 34 in an opposing direction from the head gimbal assemblies 30. The coil portion 42 interacts with a pair of permanent magnets 43 mounted the housing enclosure 16 to form a voice coil motor for rotating the actuator assembly 28 about the pivot axis 36. Thus, the voice coil motor controllably positions the head 40 relative to the disk surface. The printed circuit board assembly 14 is disposed in electrical communication with the head 40. Electrical connections extend from each of the heads 40 along the attached gimbals and load beams and commonly terminate at an integrated circuit 44 mounted to a side of the body portion 34 of the actuator assembly 28. The integrated circuit 44 includes apre-amplifier for increasing electrical signals sent to and received from the head 40. In addition, the integrated circuit 44 is disposed in electrical communication with the coil portion 42 for transmitting current thereto. The flex cable assembly 32 includes a flex cable 46, a flex clamp 48 and electrical components (e.g., the integrated circuit 44 containing a pre-amplifier). The flex cable 46 includes the flex cable portion 47. The flex cable 46 is interposed between the printed circuit board assembly 14 and the integrated circuit 44.
In operation, the printed circuit board assembly 14 which includes the disk controller 52 for generating a servo control signal which is transmitted to the integrated circuit 44 via the flex cable 46 which in turn is electrically communicated to the coil portion 42. As such, the actuator assembly 28 is rapidly pivoted in a back and forth motion about the pivot axis 36 so as to controllably position the heads 40 adjacent to the selected ones of the tracks on the disk surfaces in response to the servo control signal. Further the servo control data from servo sectors is read by the heads 40 to generate position error information (a position error signal) which is representative of the positioning of the heads 40 relative to particular tracks during a track-follow operation. Such electrical signal is transmitted to the integrated circuit 44 which in turn transmits a corresponding electrical signal to the printed circuit board assembly 14 via the flex cable 46. The printed circuit board assembly 14 receives the electrical signal and generates a signal which is representative of the read data read from the servo sectors. The printed circuit board assembly 14 uses the position error signal to control the movement of the actuator assembly 28.
The head stack assembly 20 includes the BC rotary actuator 50. The BC rotary actuator 50 has a BC actuator weight distribution specification which defines a BC rotary actuator center-of-gravity 54 as shown in
Importantly, it is recognized that mitigation of the effects of the installation-induced torque vector 62 reduces external acceleration applied to the BC rotary actuator 50 about the pivot axis 36 due to external linear acceleration experienced by the disk drive 10 during a track-follow operation. As such, the BC rotary actuator center-of-gravity 54 of the BC rotary actuator 50 is displaced from the pivot axis 36 by a distance and a direction defined by the installation-induced torque vector 62 when the rotatable BC HSA portion 21 is connected in the disk drive 10 for mitigating external acceleration applied to the BC rotary actuator 50 about the pivot axis 36 due to external linear acceleration experienced by the disk drive 10 during a track-follow operation. The method of determining the location of the BC rotary actuator center-of-gravity 54 is discussed in detail below and generally includes a process of taking into account the installation-induced torque vector 62 by utilizing position error information.
Referring now to
It is contemplated that a test rotary actuator center-of-gravity torque vector 58 is associated with the test rotary actuator center-of-gravity 54' as symbolically depicted in
According to an aspect of the method of the present invention, there is provided a method of making the BC rotary actuator 50 having reduced imbalance characteristics thereof based upon track-follow characteristics of the test HSA portion 21'. Referring now to the symbolic
Position error information in the form of a position error signal (PES) is read or otherwise collected by the test head 40' while the track-follow operation regarding a selected disk track 23' is performed while subjected to the vibrational input.
In order to increase the sample size and accuracy of the data collected, the vibration and acceleration data may also be collected with regard to additional test disk drives having additional test rotary actuators, such as test disk drive 70', which is similarly configured as the test disk drive 70. Additionally, the forgoing vibrational testing is preferably repeated with the test disk drives 70, 70' being rotated by 90 degrees in the rotation plane of the test rotary actuator 50'.
Calculating Resultant Torque Vector from Read Position Error Information
Head off-track error due to vibration of the test disk drive 70 is determined from the read position error information representative of positioning of the test head 40' relative to the selected disk track 23'. Such position error information can then be used to calculate a magnitude of a resultant torque vector 60, as further discussed below. However, as one of ordinary skill in the art will appreciate, the determination of the head off-track error from the read position error information is challenging due to random noise signals introduced into the system. For example, referring to
FFT Technique for Determining Head Off-Track Error
In summary, as further discussed below, the Fast Fourier Transform (FFT) technique includes the following steps:
1. Transforming read position error information to frequency domain by applying a Fast Fourier Transform algorithm to obtain a power spectral density of the read position error information;
2. Calculating a peak amplitude of the head off-track error due to the vibration of the disk drive based upon an amplitude of the power spectral density at the predetermined frequency of the vibration of the disk drive 70; and
3. Converting the peak amplitude to a percent off-track;
The read position error information is time domain data. Such time domain data may be transformed into the frequency domain. For a periodic time signal f(t) with period (T) and frequency (w), its Fourier transform (FFT(w)) is defined as (1/T) multiplied by the integral from zero to T of f(t) e-jwtdt. As one of ordinary skill in the art will appreciate, as a result of the integral, the absolute value of f(t) is the absolute value of the FFT(w) at peak frequency multiplied by a factor of two (2).
Having transformed the time domain data to frequency domain data, a Fast Fourier Transform algorithm may be applied to the frequency domain data. Next, a power spectral density of the frequency domain data may be generated as a function of frequency.
Iterative Rectified Signal Approach for Determining Head Off-Track Error
While the forgoing Fast Fourier Transform technique is a preferred embodiment of the method of the present invention, it is contemplated that other techniques and methods may be utilized to perform the off-track calculation. For example, the off-track calculation may follow an iterative rectified signal approach. Such approach begins with the initial step of rectifying the position error information due to vibration to produce a rectified position error information. The mean of the rectified position error information is determined. Then, the test disk drive 70 is used to perform a track-follow operation without vibrational input and baseline position error information is read. In this respect, such baseline position error information is representative of baseline noise of the system. The amplitude of a sinusoidal head off-track error due to a vibration of the disk drive 70 is guessed. A guessed sinusoidal signal is determined having the initially guessed amplitude and a frequency equal to the predetermined input frequency of vibration of the test disk drive 70. The guessed sinusoidal signal is added to the read position error information signal to produce a combined signal. The combined signal is rectified and a mean amplitude value is determined. This mean amplitude value is compared with the mean amplitude of the rectified read position error information. This process is continued interatively until the two mean amplitude values are the same, at which point the finally guessed amplitude as iteratively derived is contemplated to be correct. The finally determined vibration amplitude is then converted to a percent off-track (vibration amplitude/track pitch×100%).
Resultant Torque Vector Calculation from Head Off-Track Error
Having determined the head off-track error, in the form of a percent off-track, such as via the above-described techniques, the magnitude of the resultant torque vector 60, as depicted in
Where, J is the inertia of the test rotary actuator 50'; R is the radial distance between the test pivot axis 36' and the test head 40', TPI is the number of tracks per inch of the disk 22'; VibG is the vibration level or amplitude of the input vibration of the shaker table 74 (in terms of G-level); arej is an unit less acceleration rejection parameter which is a function of frequency and an acceleration rejection curve, as discussed below. Interestingly, the magnitude of the resultant torque vector 60 is proportional to the inertia of the test rotary actuator 50', and inversely proportional to the radial distance between the test pivot axis 36' and the test head 40', the number of tracks per linear distance, the vibration amplitude of the input vibration of the shaker table 74 and the acceleration rejection parameter.
The acceleration rejection parameter (arej) is obtained from an acceleration rejection Bode plot at the vibration frequency. The acceleration rejection Bode plot is a plot of the magnitude ratio of the angular position of the test head 40' to the input disturbance torque (i.e., input from the servo motor) per unit inertia applied to the test rotary actuator 50' at different frequencies. The acceleration rejection curve is dependent on the bandwidth and system dynamics. The value corresponding to the predetermined vibration frequency is used in the equation.
Determining Test Installed HSA Portion Center-of-Gravity from Collected Vibrational Data
Given a magnitude of the resultant installed torque vector 60, it is necessary to determine the location of the test installed HSA portion center-of-gravity 56 in order to know where to add or subtract mass in order to properly "balance" the design of the test rotary actuator 50'. In this regard, such "balancing" is to reduce the distance between the test installed HSA portion center-of-gravity 56 and the test pivot axis 36', with the ultimate goal of co-locating the two locations. As mentioned above, position error data is collected while the track-follow operation is preformed while the disk drive 70 subjected to the vibrational input. Such collected position error data is used to calculate a location of the test installed HSA portion center-of-gravity 56.
Based on saved plots from an oscilloscope, a phase relationship can be derived between the acceleration vibrational input to the shaker table 74 and a low-passed PWM position error output of the test disk drive 70. By using this phase relationship, two possible quadrants in which the effective imbalance could exist are determined with respect to a y-axis of vibration. The same test could be done for an x-axis. The overlapping of the possible quadrants (in a test disk drive 70 coordinate system) for the x and y direction vibration uniquely determines the quadrant where the effective imbalance resides. Thus, the location of the total effective imbalance and the test installed HSA portion center-of-gravity 56 in a test disk drive 70 coordinate system is uniquely determined.
The forgoing techniques are used to determine the coordinates of the test installed HSA portion center-of-gravity 56 resolved in a Cartesian coordinate system relative the test disk drive 70. However, because the test rotary actuator 50' rotates about the test pivot axis 36', the coordinates of the imbalance change as the test head 40' is positioned over varying disk track locations. In this regard, it is contemplated that the location of the test installed HSA portion center-of-gravity 56 must be converted to a coordinate system relative to the test rotary actuator 50', and more particularly to the test actuator weight distribution specification upon which the test rotary actuator 50' is modeled. It is contemplated that a transformation matrix may be utilized to convert the location of the test HSA portion installation center-of-gravity 56 to such test rotary actuator 50' coordinates.
Deriving Installation-Induced Torque Vector and Balancing Torque Vector
As described above, the magnitude of the resultant torque vector 60 is based upon the read position error information. By definition, the resultant torque vector 60 has a magnitude equal to a mass of the test rotary actuator 50' times a distance from the test pivot axis 36' to the test installed HSA portion center-of-gravity 56, and the resultant torque vector 60 has a direction emanating from the test pivot axis 36' towards the test installed HSA portion center-of-gravity 56. Referring now to the vectorial diagram of
Referring now to
The vectorial addition of the balancing torque vector 66 with the test rotary actuator center-of-gravity torque vector 58 produces a BC rotary actuator center-of-gravity torque vector 64. It is contemplated that the magnitude of the BC rotary actuator center-of-gravity torque vector 64 is equal to the mass of the test rotary actuator 50' times a distance from the test pivot axis 36' to the BC rotary actuator center-of-gravity 54. In this regard, a BC rotary actuator 50 is constructed having mass characteristics such that its center-of-gravity is located at the determined BC rotary actuator center-of-gravity 54. Thus, the balancing torque vector 66 is incorporated into the test actuator weight distribution specification to produce a BC actuator weight distribution specification. The BC actuator weight distribution specification may be used to manufacture the BC rotary actuator 50 as shown in FIG. 6a. As such, the BC rotary actuator 50 has a pivot axis 36 and a BC rotary actuator center-of-gravity 54 displaced from the pivot axis 36. Such incorporation may be effectuated by any of those methods chosen from those which are well known to one of ordinary skill in the art. In this regard, as the BC actuator weight distribution specification will typically be designed with the aid of a computer model, such computer model may be modified to account for changes in the mass characteristics of the rotary actuator design so as to selectively add and subtract mass at various locations. In so doing, the location of the BC rotary actuator center-of-gravity 54 may be manipulated in comparison to the test rotary actuator design. As a consequence of such manipulation, the BC installed HSA portion center-of-gravity 68 is co-located with the pivot axis 36, as shown in
Advantageously, the forgoing method of making the BC rotary actuator 50 is nondestructive with regard to its utilization of the test rotary actuator 50' and test disk drive 70. This tends to reduce development time and cost of the BC rotary actuator 50 in comparison to those prior art methods which include physically cutting the flex cable. Additionally, the forgoing method of making the BC rotary actuator 50 uniquely adapted to compensate for the installation-induced torque vector as it incorporates feedback data in the form of actual testing positional error information. As such, all components of the installation-induced torque vector is compensated for not just those associated with the flex cable mass.
Casey, Shawn E., Codilian, Raffi
Patent | Priority | Assignee | Title |
6571460, | Jul 31 2000 | Western Digital Technologies, Inc. | METHOD AND APPARATUS FOR BALANCING A ROTARY ACTUATOR BY MODIFYING WEIGHT DISTRIBUTION CHARACTERISTICS OF THE ROTARY ACTUATOR FOR LOCATING AN INSTALLED HEAD STACK ASSEMBLY PORTION CENTER-OF-GRAVITY ALONG A PIVOT AXIS |
6690533, | Feb 24 2000 | Seagate Technology LLC | Drive level actuator imbalance torque test |
6975480, | Apr 17 2002 | Western Digital Technologies, Inc. | Method for determining repeatable runout cancellation values in a magnetic disk drive using filtering |
7054111, | Nov 18 2002 | HITACHI GLOBAL STORAGE TECHNOLOGIES NETHERLANDS B V | Disk drive actuator-pivot assembly with corrugated rings |
7196864, | Jun 15 2005 | Western Digital Technologies, Inc. | Disk drive having a servo control system optimized for faster determination of repeatable runout correction values and related method |
7667931, | Mar 20 2006 | BENHOV GMBH, LLC | Flexible electrical interconnection with ends urged into engagement with curved surfaces of a support and hub in a miniature hard disk drive and method |
8116038, | May 13 2010 | Western Digital Technologies, Inc.; Western Digital Technologies, INC | Depopulated disk drive head stack assembly having a necked dummy mass with relief alcoves |
8223453, | Jul 29 2008 | Western Digital Technologies, INC | Disk drive having a vibration absorber with fixed free ends |
8553367, | Aug 12 2008 | Western Digital Technologies, INC | Depopulated head stack assembly having a necked dummy mass |
8908319, | Apr 18 2013 | Western Digital Technologies, INC | Disk drive with slow acting desiccant |
8908325, | Mar 08 2013 | Western Digital Technologies, Inc. | Threaded disk clamping element with step on disk contact surface |
8941952, | Jun 10 2014 | Western Digital Technologies, INC | Disk drive head stack assembly having a flexible printed circuit with bond pads having reduced capacitance |
8970984, | Apr 29 2014 | Western Digital Technologies, Inc. | Grooved cylindrical seal with increased radial clearance for reduced cost disk drive spindle |
8995094, | Feb 28 2014 | Western Digital Technologies, INC | Disk drive head suspension with a dual dimple and a flexure tongue with a piezoelectric microactuator |
9007716, | Sep 24 2012 | Western Digital Technologies, Inc. | Spindle motor magnet diameter increase above head plane |
9019657, | Mar 13 2013 | Western Digital Technologies, INC | Coined VCM tab to limit cover deflection under pinch load |
9025284, | Feb 26 2014 | Western Digital Technologies, INC | Disk drive with self sealing screw attachment of actuator pivot |
9036295, | Dec 20 2011 | Western Digital Technologies, Inc. | Information storage device with a damping insert sheet between a housing bay and a disk drive |
9058851, | Jul 02 2014 | Western Digital Technologies, INC | Information-storage device including an oxygen absorbing device |
9099131, | Mar 17 2010 | Western Digital Technologies, Inc. | Suspension assembly having a microactuator electrically connected to a gold coating on a stainless steel surface |
9099153, | Apr 03 2013 | Western Digital Technologies, INC | Storage device with a cover supporting portion |
9116066, | Apr 27 2012 | Western Digital Technologies, INC | Devices and methods for system-level disk drive vibration and shock testing |
9123387, | Aug 21 2014 | Western Digital Technologies, INC | Magnetic recording drives with active photocatalytic filtration |
9129639, | Nov 08 2012 | Western Digital Technologies, Inc. | Method of imbalance correction using a grooved disk clamp |
9147436, | Apr 25 2012 | Western Digital Technologies, Inc. | Slim form factor disk drive comprising disk drive enclosure having an insular raised region |
9153262, | Mar 26 2015 | Western Digital Technologies, INC | Disk drive actuator having a radially stepped pivot bore |
9159205, | Dec 18 2013 | Western Digital Technologies, INC | Tamper-evident seals having adhesive-free areas to minimize rework time |
9165580, | Dec 10 2013 | Western Digital Technologies, INC | Disk drive head suspension tail with stiffened edge alignment features |
9171560, | Sep 26 2014 | Western Digital Technologies, INC | Sloping transition on a ramp of a hard disk drive |
9171583, | Mar 23 2015 | Western Digital Technologies, INC | Disk drive having a top cover channel vented to a central cavity via a peripheral clearance gap |
9183889, | Mar 23 2015 | Western Digital Technologies, INC | Disk drive having a top cover channel vented to a central cavity via a hole through a bottom land |
9190114, | Feb 09 2015 | Western Digital Technologies, INC | Disk drive filter including fluorinated and non-fluorinated nanopourous organic framework materials |
9196275, | Mar 12 2014 | Western Digital Technologies, INC | Magnetic head separator fin material to prevent particulate contamination on slider |
9196292, | Feb 05 2015 | Western Digital Technologies, INC | Rotary spindle having a disk clamp bottom land facing and in contact with a shaft top land |
9196301, | Oct 14 2011 | Western Digital Technologies, Inc. | Suspension clamp for clamping a disk drive suspension to an actuator arm |
9208825, | Aug 07 2013 | Western Digital Technologies, Inc. | Disk drive having a conformal peripheral foil seal having an opening covered by a central metal cap |
9214174, | Oct 29 2010 | Western Digital Technologies, Inc. | Method of manufacturing a disk drive head gimbal assembly having a flexure tail with folded bond pads |
9263070, | Nov 05 2014 | Western Digital Technologies, INC | Actuator pivot assembly including a bonding adhesive barrier configured to reduce contamination |
9299384, | Aug 02 2012 | Western Digital Technologies, INC | Ultra-thin HDD embedded disk clamp design |
9305599, | Apr 03 2013 | Western Digital Technologies, Inc. | Storage device with a cover supporting portion |
9324344, | Dec 10 2013 | Western Digital Technologies, INC | Disk drive head suspension tail with ground pad outside of bonding region |
9330695, | Dec 10 2013 | Western Digital Technologies, INC | Disk drive head suspension tail with a noble metal layer disposed on a plurality of structural backing islands |
9379311, | Dec 09 2005 | Western Digital Technologies, Inc. | Apparatus for manufacturing piezoelectric actuators |
9390736, | Mar 13 2014 | Western Digital Technologies, INC | Magnetic head separator connected to a ramp |
9406333, | Nov 10 2015 | Western Digital Technologies, Inc. | Disk drive having a stationary plate between disks with grooves adjacent fastener holes |
9472218, | Mar 17 2010 | Western Digital Technologies, Inc. | Suspension assembly having a microactuator electrically connected to a gold coating on a stainless steel surface |
9472242, | Jun 05 2015 | Western Digital Technologies, Inc. | Hard disk drive enclosure base with feed through flexure design and accompanying flexure |
9508393, | Jun 25 2015 | Western Digital Technologies, Inc. | Hard disk drive enclosure base with a helium sealed gasket |
9514773, | Aug 20 2008 | Western Digital Technologies, Inc. | Head stack assembly with a flexible printed circuit having a mouth centered between arms |
9524738, | Jun 25 2015 | Western Digital Technologies, INC | Disk drive head gimbal assembly having a flexure tail with a dielectric layer that has regions of lesser thickness |
9530439, | Dec 10 2013 | Western Digital Technologies, Inc. | Disk drive head suspension tail with stiffened edge alignment features |
9564156, | Jan 27 2016 | Western Digital Technologies, Inc. | Head gimbal assembly having a flexure tail with cover layer standoff islands |
9633680, | Oct 29 2010 | Western Digital Technologies, INC | Head suspension having a flexure tail with a covered conductive layer and structural layer bond pads |
9662753, | Mar 10 2014 | Western Digital Technologies, INC | Disk drive spindle with fluid journal bearing having increased radial clearance in axial end regions |
9881640, | Dec 10 2013 | Western Digital Technologies, INC | Disk drive head suspension tail with a noble metal layer disposed on a plurality of structural backing islands |
9908167, | Mar 02 2015 | Western Digital Technologies, INC | Disk drive tolerance ring with edge rounding from opposite major faces |
9953667, | Oct 29 2010 | Western Digital Technologies, Inc. | Disk drive system |
Patent | Priority | Assignee | Title |
4772974, | Jun 04 1985 | QUANTUM CORPORATION, A CORP OF DE | Compact head and disk assembly |
5953183, | Nov 17 1997 | BANKBOSTON, N A , AS AGENT | Head stack assembly for a magnetic disk drive with a pass-through flex circuit cable |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
May 31 2000 | Western Digital Technologies, Inc. | (assignment on the face of the patent) | / | |||
Sep 12 2000 | CASEY, SHAWN E | Western Digital Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011443 | /0348 | |
Sep 15 2000 | CODILIAN, RAFFI | Western Digital Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011443 | /0348 | |
Sep 20 2000 | Western Digital Corporation | General Electric Capital Corporation | SECURITY AGREEMENT | 011170 | /0948 | |
Apr 06 2001 | Western Digital Corporation | Western Digital Technologies, INC | AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF WESTERN DIGITAL CORP | 011967 | /0481 | |
Aug 09 2007 | GENERAL ELECTRIC CAPITAL CORPORATION, AS AGENT | Western Digital Technologies, INC | RELEASE BY SECURED PARTY SEE DOCUMENT FOR DETAILS | 021502 | /0451 | |
May 12 2016 | Western Digital Technologies, INC | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | SECURITY AGREEMENT | 038744 | /0281 | |
May 12 2016 | Western Digital Technologies, INC | JPMORGAN CHASE BANK, N A , AS COLLATERAL AGENT | SECURITY AGREEMENT | 038722 | /0229 | |
Feb 27 2018 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Western Digital Technologies, INC | RELEASE BY SECURED PARTY SEE DOCUMENT FOR DETAILS | 045501 | /0714 | |
Feb 03 2022 | JPMORGAN CHASE BANK, N A | Western Digital Technologies, INC | RELEASE OF SECURITY INTEREST AT REEL 038744 FRAME 0481 | 058982 | /0556 |
Date | Maintenance Fee Events |
Jul 13 2005 | M1551: Payment of Maintenance Fee, 4th Year, Large Entity. |
Aug 22 2009 | M1552: Payment of Maintenance Fee, 8th Year, Large Entity. |
Aug 16 2013 | M1553: Payment of Maintenance Fee, 12th Year, Large Entity. |
Date | Maintenance Schedule |
Feb 26 2005 | 4 years fee payment window open |
Aug 26 2005 | 6 months grace period start (w surcharge) |
Feb 26 2006 | patent expiry (for year 4) |
Feb 26 2008 | 2 years to revive unintentionally abandoned end. (for year 4) |
Feb 26 2009 | 8 years fee payment window open |
Aug 26 2009 | 6 months grace period start (w surcharge) |
Feb 26 2010 | patent expiry (for year 8) |
Feb 26 2012 | 2 years to revive unintentionally abandoned end. (for year 8) |
Feb 26 2013 | 12 years fee payment window open |
Aug 26 2013 | 6 months grace period start (w surcharge) |
Feb 26 2014 | patent expiry (for year 12) |
Feb 26 2016 | 2 years to revive unintentionally abandoned end. (for year 12) |